Left 4 DeadLeft 4 Dead is a cooperative first-person shooter video game. It was developed by Turtle Rock Studios, which was purchased by Valve Corporation during development. The game uses Valve's proprietary Source engine, and is available for Windows and the Xbox 360. Development on the game was completed on November 13, 2008 and was released on November 18, 2008 in the United States and on November 21, 2008 in Europe.Set during the aftermath of an apocalyptic pandemic, the game pits its four protagonists—dubbed the "survivors"—against hordes of the infected, zombie-like aggressive mutants. There are four game modes: a single-player mode in which allied characters are controlled by AI; a four-player, co-op campaign mode; an eight-player online versus mode; and a four-player survival mode. In all modes, an artificial intelligence (AI), dubbed the "Director", controls level pacing and item spawns, in an attempt to create a dynamic experience and increase replay value.Left 4 Dead was well received by the industry media upon its release, with praise given for its replay value, focus on cooperative play, and movie-like experience. Several criticisms were aimed at limited level selection and the lack of a narrative. The game has won several publication awards, as well as distinctions from the Academy of Interactive Arts & Sciences and British Academy of Film and Television Arts. As was done with Team Fortress 2, Valve plans on supplementing the game with free downloadable content. The first of these, called the "Survival Pack", was released on April 21, 2009.

GameplayLeft 4 Dead is a first-person shooter, though it makes use of the third-person perspective during cut scenes and some player actions. In campaign mode, the player takes control of one of the survivors; if four human players are not available, then the remaining survivors are AI-controlled bots. They play through the levels fighting off the infected—living humans who have been infected with a mutagenic, rabies-like virus to which the survivors are immune.

The game is focused on cooperation and team play; colored outlines of teammates are visible through walls to help players stick together and coordinate their movement. If a survivor falls off a ledge, then they may automatically hang onto it and can only be helped up by another survivor. If a survivor's health is depleted, then they become incapacitated and can only be revived by another survivor, at which point they continue playing with a low amount of health that decreases over time. If a survivor has been incapacitated and revived twice without tending to their wounds, then they will experience distorted black-and-white vision, and the next incapacitation will kill the character. If a survivor incurs enough damage while incapacitated, or is not eventually helped up by teammates, then the incapacitated character will die. If a survivor is killed, then they will respawn in a closet or other enclosed space after a period of time (except during key points in the scenario), but must be freed by another survivor to rejoin the team. Otherwise, the player must wait until the next level. Survivors can share first-aid kits and pain pills and help each other heal. Left 4 Dead has friendly fire that cannot be disabled, increasing the need for caution around other survivors. On the easy difficulty level, friendly fire does not harm teammates but still registers as having occurred with a notice on the screen saying, "Don't shoot teammates!"

The survivors communicate by voice commands that are accessed by quick menus, and some sound off automatically when performing actions such as reloading or spotting infected. Over 1,000 unique lines have been recorded for each survivor. Additional communication of player actions is conveyed through character lights. Also, weapon-mounted flashlights and muzzle flashes help the players in determining whether their companions are shooting, performing melee attacks, reloading or moving. Due to control issues and the likelihood of players using a LIVE headset, the Xbox 360 version of Left 4 Dead omits the quick phrases feature.

The game is experienced through four campaigns that take place in various urban and rural locales. Multiple visual in-game hints—including license plates, park signs, and markings on airport equipment—imply that these locations are in Pennsylvania, and similarly a memorial wall giving names of those who have died in the infection (actually names of the game's development team) along with their dates of birth and death suggests that the game takes place in October 2009. Each campaign is divided into five chapters marked by safe rooms, which are checkpoints where players can heal, re-arm and revive characters who were killed. Specifically, the four campaigns are: "No Mercy", an urban setting culminating in a hospital skyscraper; "Death Toll", a small-town and countryside setting; "Dead Air", an airport setting; and "Blood Harvest", a woodland and farm setting. The levels are essentially linear, with distinct beginnings and ends, but there are a number of alternate routes to follow with more supplies, helping to create a sense of non-linearity. In the final chapter of each campaign, the players must defend a position from an onslaught of infected until rescue arrives. Each campaign typically lasts between 35 and 75 minutes depending on the difficulty level. The Windows and Xbox 360 versions of the game both contain achievements.

Survivor charactersThere are four playable human characters in the game: Francis (voiced by Vince Valenzuela), a tattoo-covered biker; Zoey (voiced by Jen Taylor), a college student and horror movie enthusiast; Louis (voiced by Earl Alexander), a junior systems analyst in his company's IT department; and Bill (voiced by Jim French), a former Green Beret and a Vietnam veteran. Early plans were for players to be randomly assigned to characters but in the final release, players can choose any character—provided that the character has not already been selected—or be randomly assigned an unselected character.

Survivors are armed with various firearms. Each player starts the game with a M1911 pistol. It has unlimited ammo and is the only weapon that the survivor can use when they are incapacitated. When a second pistol is found, the player can dual wield them. At the beginning of each campaign, the player can choose between an Uzi submachine gun and a pump-action shotgun. As the survivors progress through a campaign, more powerful weapons can be found: the M16A3 assault rifle, Benelli M4 Super 90 semi-automatic shotgun and a scoped Ruger Mini-14 hunting rifle. In addition to firearms, a player can also carry three other items in their inventory: improvised grenades (either a Molotov cocktail to create a wall of fire or a pipe bomb, modified with an attached smoke alarm designed to attract the infected to it before it explodes); a first-aid kit, which can be used to heal any survivor; and pain pills, which provide temporary health that depletes gradually and quicker with damage from infected, and can be handed to teammates for later use. Regardless of what weapon or item a player is using, a melee attack can be used to shove away any infected within reach. Also available are environmental weapons, such as gasoline cans, oxygen cylinders and propane tanks, which explode when shot. These can be picked up, moved and used as a melee weapon by the survivors, but while carrying an object they cannot use their weapons or health items.

Infected charactersThe infected (voiced by experimental musician Mike Patton) are the survivors' foes in Left 4 Dead, and they appear to be partly inspired by the infected from several modern films, including 28 Days Later. An important distinction is that the infected are not traditional undead zombies, but rather living humans infected with a rabies-like pathogen. They are never seen eating human flesh or brains, as traditional zombies are generally portrayed to do, instead simply single-mindedly attacking the survivors. In an interview with 1Up.com, Mike Booth commented on the concept of using a pathogen as an inspiration for the setting:

“Even though we obviously pushed well beyond the realm of believability with many of our "boss" infected, the core idea of a mind-destroying, civilization-collapsing pathogen is more horrifying to me than magically animated corpses, precisely because it is plausible. Rabies is a good example of a pathogen that can turn a loyal, friendly, protective family pet into a slavering attack machine. It's a virus that reprograms the behaviors of a complex animal – a mammal, in fact. What if something similar happened to humans? Left 4 Dead is one possible answer.”

The common infected encountered during the game are fast and agile, weak individually, but may be overwhelming in numbers. They display a special attraction to high-pitched alarm-type sounds, such as the beeping device attached to pipe bombs and car alarms. Common infected will often chase down the source of these noises while ignoring lower-pitched, but much louder sounds such as gunfire. They occasionally attack en masse, referred to in-game as a "horde".

In addition to the common infected, there are five "special" or "boss" infected whose mutations grant them special attacks that make them much more dangerous: the hunter, an agile infected that can pounce on survivors from a great distance; the smoker, an infected that ensnares survivors with its long tongue at a distance and, upon death, releases a cloud of smoke that obscures vision and blocks voice commands and voice communication; the boomer, a bloated infected whose vomit and bile (which may be released at will and upon death) blinds the player briefly and attracts a horde; the tank, a huge, muscular infected that is the most powerful and difficult to kill; and the witch, a passive female infected, who, when provoked by loud sounds, lights, gunshots, a survivor approaching too closely, and general stimulation will trigger her to attack her provoker. She is able to knock down the provoker in one hit and will quickly kill them if not killed herself. The victims of some of these attacks require assistance from a teammate before they can regain control. Each of the special infected, as well as approaching hordes, have a distinctive sound or a timely musical cue, making their presence easily recognizable by players.

In versus mode, four additional players can take control of the special infected—apart from the witch, which remains computer-controlled. Each infected player is randomly assigned a class of special infected when they enter a spawn mode. While in spawn mode, the infected can quickly roam around the map in search of an appropriate place in which to spawn. This location must be sufficiently distant from any survivor, out of the line of sight of any survivor, and outside restricted areas such as safe rooms. Upon death, the infected player must wait up to 20–30 seconds before reentering spawn mode, depending on how many players are on the infected team. When a tank is spawned in the game, infected players receive a message indicating which player will control it. The human-controlled infected can see their teammates' outlines through walls similar to the survivors, but can also see each survivor's outline, which is colored according to the survivor's health and fades out if the survivor refrains from attacking, running and vocalizing. Vertical pathways exclusive to the infected, such as pipes and vines, are marked with animated symbols for the infected players. These can be climbed and used for ambushes.

AI and the DirectorThe artificial intelligence of Left 4 Dead features a dynamic system for game dramatics, pacing and difficulty called the "Director". Instead of fixed spawn points for enemies, the Director places enemies and items in varying positions and quantities based upon each player's current situation, status, skill and location, creating a new experience for each play through. The Director also creates mood and tension with emotional cues, such as visual effects, dynamic music and character communication. Valve has termed this dynamic set-up "procedural narrative".

In addition to the AI Director, there is a second Director that controls music. It was created as a way to keep the music interesting throughout the game. The music Director monitors what a player has experienced to create an appropriate mix. The process is client-side and done by a multi-track system. Each player hears their own mix, which is being generated as they play through the game, and dead players watching a teammate hear their teammates' mix.

Game modesLeft 4 Dead contains four game modes: campaign, versus, survival, and single-player. The cooperative campaign consists of four human-controlled survivors who attempt to make their way between safe rooms and eventually to rescue. In this mode, the special infected are controlled by the AI. In a versus campaign, each team of four players plays each chapter of the campaign as both survivor and infected, swapping sides once per chapter. Unlike campaign mode, dead survivors do not respawn. If at least one survivor finishes the chapter, then the team playing the survivors earns points according to their average progress through the chapter, as well as bonus points based on their health and the health items in their inventory. These points are then multiplied by the chapter's difficulty level, and the number of survivors who finished. If all the survivors are killed, then they only earn progress points and the difficulty multiplier. Survival mode consists of a timed challenge where players try to survive as long as possible against a never-ending flood of the infected. Single-player mode is basically the same as campaign mode, but with three AI-controlled bots as the other survivors.

ProductionDevelopment on Left 4 Dead started in mid-2005. Valve aimed to create a horror film-inspired game that merges single player games' character-driven narrative structure with multiplayer games' social interaction and high replayability. The game was first revealed in the Christmas 2006 publication of PC Gamer UK with a six-page article describing a playthrough at Valve's headquarters. A teaser was released with The Orange Box. The game was first playable at the Showdown 2007 LAN in San Jose and at QuakeCon 2007. Turtle Rock Studios announced Left 4 Dead on November 20, 2006, and was acquired by Valve Corporation on January 10, 2008, because of the game and long-standing relationship between the companies. The game opened up to pre-purchasing on Valve's Steam system on October 15, 2008.

To give Left 4 Dead significant exposure, Valve financed a $10-million marketing campaign for the game in the United States and Europe, with advertisements appearing on television, print, websites and outdoor placements in many cities. Valve also hosted photo contests called, "Dude, where's my thumb?" offering copies of Left 4 Dead to people who submitted the best picture involving zombies or the outdoor advertising.

When asked a short while after the release of the game about the planned availability of a Source development kit (Level editor for Valve's Source game engine) for Left 4 Dead, Chet Faliszek from Valve replied it was planned "shortly".

DevelopmentLeft 4 Dead uses the latest version of Valve's Source engine, with improvements such as multi-core processor support and physics-based animation to more realistically portray hair and clothing, and to improve physics interaction with enemies when shot or shoved in different body parts. Animation was also improved to allow characters to lean realistically when moving in curved paths. Rendering and artificial intelligence were scaled up to allow for a greater number of enemies who can navigate the world in better ways, such as climbing, jumping or breaking obstacles. Lighting was enhanced with new self-shadowing normal mapping and advanced shadow rendering that is important to convey information about the environment and player actions. Wet surfaces and fog are used to create mood. Many kinds of post processing cinematic visual effects inspired by horror movies have been added to the game. There is dynamic color correction that accentuates details based on importance, contrast and sharpening to focus attention on critical areas, film grain to expose details or imply details in dark areas and vignetting to evoke tension and a horror-film look.

To facilitate Left 4 Dead's goal of replayability Valve created an artificial intelligence system called the "AI Director" to dynamically modify game dramatics, pacing and difficulty. This artificial intelligence dynamically places enemies, items and weapons in varying amounts and locations depending on the groups status and skill. The Director can also create mood and tension by triggering music, visual effects and character communication. A secondary client side music director exists that creates an appropriate musical mix for each player based on what they have experienced in the game and dead players watching a teammate hear their teammates' mix. All of these work together to try and create a new experience for each play through of the game.

Left 4 Dead underwent many phases of development; influenced by playtesting, Valve removed many of the features that were originally in the game. In the initial phases, there was another special infected, called the "screamer", which had no attacks but upon spotting a survivor would run to a safe place and then emit a loud scream that attracted a horde of infected. This infected class was removed, but its ability to attract the horde was incorporated into the boomer's vomit. A persistent merit/demerit system was envisioned to provide positive feedback for good behavior, such as aiding a fallen teammate; and negative feedback for poor behavior, such as shooting a teammate. This would provide a score to rank a player's effectiveness as a teammate, but this system was removed late in the development of the game in favor of immediate, non-persistent feedback displayed in-game. Another significant element removed was a continuous narrative between campaigns; because the game is designed for replayability, it was difficult to hold the player's attention for repeated viewings of cut scenes, so they were dropped in favor of a sparse narrative. Also, the game started out with one big city design with many routes for the survivors, but playtesters were confused when they began to play, and later they always chose the same route; ultimately Valve cut the city maps into the first "No Mercy" and "Dead Air" campaigns.

Certain Affinity assisted Valve with the Xbox 360 version of the game. The Xbox 360 version of Left 4 Dead has the same game modes as the PC version but has additional features such as support for Split screen, allowing for two players to play offline and online from the same console, and System Link play. Split-screen mode can also be achieved on the PC version, but it requires console commands and may require the modification of controller configuration files; and it is not officially supported by Valve. Both versions of the game have a new matchmaking system to simplify the process of finding other players. This new server management system was met with a negative reaction from PC server operators, who, with this system, had very little control over their servers. This led to Valve releasing a series of patches that allowed server operators to remove their server from the matchmaking "pool" of servers or make private servers. Valve runs dedicated servers for both versions of the game.

PromotionTo promote the game and provide basic training to player before starting the game, Valve chose to develop a pre-rendered intro movie. This movie was released on Halloween and shows events prior to the beginning of the "No Mercy" campaign. Valve chose an intro movie over in-game training mechanics because they wanted the players to be immediately dropped into a zombie apocalypse. Valve later detailed in their official Left 4 Dead blog how they designed the movie, from an intentionally very basic animation in the beginning of July 2008 to the final result for the launch of the game.

Early access to the Left 4 Dead demo for people who pre-ordered the game began on November 6, 2008, for both Windows and Xbox 360. It gave users access to both online and single-player play in two "scenes" in one "movie" within the game. This promotion was being offered in addition to the ten percent savings for those who pre-order and applies to all Steam Windows pre-orders and all Windows and Xbox 360 pre-orders from GameStop and EB Games in North America. On November 11, the Left 4 Dead demo was made available to all Windows and Xbox 360 gamers worldwide. The Left 4 Dead demo was removed for both the Xbox 360 and Windows after the game's release on November 18 2008.

The demo had many server problems when it launched, primarily Valve's strategy for server management which made it impossible to set up a dedicated private server with administrator controls. However, a stream of patches led to the availability of a server browser and basic private server functionality as well as Valve's acknowledgment of player concerns. It appears that a patch released just before the game itself has resolved many of the connection issues that demo players were having.

On May 1, 2009, Valve allowed all Steam users to play the game for free for 24 hours. Similar to Team Fortress 2, Steam also put the game on a temporary forty percent off sale after releasing the Survival Mode update.

Release and beyondLeft 4 Dead went gold on November 13, 2008, and was released on November 18, 2008, in the United States; and on November 21, 2008, in Europe to coincide with the tenth anniversary of the release of Half-Life.

Valve released a server patch in December 2008 to stop players on Xbox Live from using PC-style cheats. A spokesperson from Valve said, "The fix is designed to halt the cheating behavior on the dedicated servers, which accounts for the majority of the co-op and versus modes of play."

Similar to Team Fortress 2, Valve intends to support the PC and Xbox 360 version of the game through free content updates. On a podcast by Kotaku, writer Chet Faliszek divulged that an announcement regarding DLC for the PC and Xbox 360 would be released "very soon", and that the announcement was delayed by the holiday season. On February 5, 2009, Valve released details about the upcoming downloadable content pack. The two full campaigns of "Death Toll" and "Dead Air" for versus mode—which were previously unavailable—are included, as well as the survival game mode, where the survivors try to survive endless waves of the infected for as long as possible. On February 11, 2009, Valve announced that the downloadable content for the game would be free for both the Xbox 360 and PC; and on April 21, it was released. Survival mode shipped with 16 maps, 15 of them being modified portions of existing maps and one being a new lighthouse-themed level titled "Last Stand".

On May 1, 2009, the game was released freely via Steam as a one-day trial called "Freaky Free Friday". The trial was then extended to end on Saturday.[citation needed] A Game Of the Year Edition of Left 4 Dead was released on the PC and Xbox 360 on May 12, 2009 with updates and new content included on the disc.

ReceptionLeft 4 Dead received almost unanimous praise from critics, with an aggregated score of 88 percent on Game Rankings and 89 percent on Metacritic. IGN stated, "It's almost pitch perfect in how it captures the tension and the action of a Hollywood zombie movie", and went on to describe it as, "quite possibly the perfect co-op shooter." Giant Bomb commented that the Source engine was beginning to show its age, but praised the game's use of lighting and filmic effects that gives the game world, "a desolate, washed-out feeling", as well as the realistic and emotive faces and the engrossing art direction. Eurogamer concluded that Left 4 Dead "is another deeply professional, personality-filled and progressive take on the shooter from Valve." Both IGN and Gamespot praised the game's replayability, but Gamespot criticized the "limited map selection" that could "sometimes feel a bit repetitious". Gamespy noted the lack of an overall narrative between the campaigns was disappointing, however some reviewers praised its faithfulness to the zombie film genre, including the "deliberately ambiguous" back-story, and the amount of characterization and emotion brought by each of the four survivors. TeamXbox commented that clipping issues hurt the otherwise "incredibly good" visual experience. Hideo Kojima, creator of the Metal Gear series declared in an interview to 1UP.com that he was "addicted to the game" which was in his view one of the "core titles made with movie-industry people that explore the depths of hi-def".

On October 28, 2008, Valve reported that preorders for Left 4 Dead had beaten those of The Orange Box by 95 percent after the Steam pre-order was launched. On November 21, 2008, the day of the game's release in Europe, Valve issued a press release stating that Left 4 Dead had exceeded the pre-order numbers of The Orange Box by over 160 percent. The Xbox 360 version of Left 4 Dead was the seventh best-selling game of December 2008 in the United States, selling in excess of 629,000 copies. On February 3, Electronic Arts revealed that Left 4 Dead had sold 1.8 million copies, excluding Steam and worldwide sales figures. On March 26, Mike Booth revealed that the game had exceeded 2.5 million sales at retail during a presentation at the Game Developers Conference 2009.

AwardsLeft 4 Dead received recognition as one of the best multiplayer and PC games of 2008 from various organizations and gaming publications. The game was named the Best Multiplayer Game of 2008 by IGN, GameSpy, Spike TV, NoFrag and BAFTA; and as the Computer Game of the Year by the Academy of Interactive Arts & Sciences (AIAS), Spike TV, and Bit-tech. Other awards include Outstanding Achievement in Online Gameplay from the AIAS, Best Use of Sound for the PC and Best Shooting game overall from IGN, Father of All FPS from Nofrag, and the best Cooperative Multiplayer and Shooter of 2008 from GameSpot who also nominated it for game of the year.

I went back to L4D1 for a little while because I got sick of L4D2. I think they added too much crap in L4D2 and the first one is overall a much better game.

I don't play either one anymore, but I would still be interested in playing once in a blue moon. I have almost 500 hours in L4D1 and a little less than 200 in the second one I think It was time for a new game, I mostly play StarCraft 2 now and a little Bad Company 2 and Team Fortress 2 here and there.

I hated TF2 at first (especially the graphics) but it's kinda of entertaining. I didn't start playing it until a few weeks ago.

L4D1 was 5 bucks a while back for a limited time. I'd keep your eyes open for those crazy limited time steam deals when games drop to rock bottom prices. I just bought borderlands for 5 bucks last week with one of those deals. Normally, it's like 30 bucks or something.

L4D1's community has sort of died after L4D2 came out, that's why so many people boycotted the sequel. You may not be able to get much playing time in on the first one even if you bought it today. Most of the players left know each other and play very competitively. Only the core hardcore fans remain (which I was at some point part of that group). Not many noobs play it I would imagine.